Research

What are "emotions," and how are they represented in the brain? What
parts of the brain are affected in emotional disorders such as
depression, anxiety or PTSD? Do all animals have emotions? If not, when
and how did emotions evolve?

The answer to each of these
important questions is that we simply do not know. The study of the
brain science of emotion is in its relative infancy, yet emotional and
psychiatric disorders continue to take an enormous toll on human
society. Current treatments for emotional disorders, such as Prozac and
related drugs, act very non-specifically on the brain and cause many
undesirable side effects. They also can take many weeks to work, and in
some patients never have any effect at all, or make symptoms worse.
Unfortunately, the pharmaceutical industry has not developed any
fundamentally new treatments for psychiatric disorders in at least two
decades. In order to develop more powerful and specific therapies for
such disorders, we need to first define the functional neural circuitry
that underlies specific emotional behaviors, so that we can understand
how it can be adversely affected. Such studies are most easily carried
out in model organisms like the vinegar fly, Drosophila melanogaster,
and the laboratory mouse. The Anderson laboratory uses both organisms
in an effort to discover evolutionarily conserved mechanisms.

Brain-scanning
studies in humans have provided powerful and impressive images of "hot
spots" of activity that occur during emotional responses. But which of
these hot spots represents the actual cause of an emotional response,
and which of them represents a reaction to the response? We cannot tell.
In order to distinguish cause from effect, it is necessary to
experimentally alter the activity of brain circuits in a highly
specific, temporally controlled manner, and determine the consequences
of such manipulations for specific emotional behaviors.

The laboratory mouse combines powerful genetics with a brain
structure that is fundamentally similar to that of humans. We are using
this system to study the neural circuits of emotional behaviors related
to fear and aggression. However mouse research is slow, costly, and
technically challenging. Moreover the complexity of the vertebrate
brain, with its 1011 neurons and 1014 synapses, is
daunting. Invertebrate model organisms, like the vinegar fly Drosophila
melanogaster, whose central brain contains less than 50,000 neurons,
are faster, cheaper, and can be used for powerful genetic screens that
are difficult to perform in the mouse. Drosophila also contains many of
the same brain chemicals found in humans and other vertebrates,
including dopamine, serotonin and acetylcholine, and uses fundamentally
similar synaptic mechanisms. But can one study "emotional" behavior in a
fly, and if so what can we learn from it that is relevant to emotional
behavior in humans? Research in this lab is aimed at addressing this
fascinating question as well.